This invention relates, in general, to humidifying gas induction or supply systems and particularly, but not exclusively, to a humidifying air induction or supply system of an internal combustion engine and a humidifying gas induction or supply system for a fuel cell.
In energy conversion systems in general, a fuel and an oxidant are combined to provide energy. In this process, chemical energy is converted into kinetic energy or electricity, as well as heat.
In internal combustion engines, including two-stroke, four-stroke, rotary and diesel motors for example, fuel-air mixtures are burnt to provide this chemical energy. Prior to combustion, the fuel may be dispersed into the induction air stream by means of direct injectors or by a carburetor, and the combustion itself may be triggered by an electrical spark, a glow-wire or simply by the heat of compression of the fuel-air mixture. In all internal combustion engines, the sudden increase in pressure caused by burning a fuel-air mixture in the combustion chamber causes parts of the engine to move, so imparting kinetic energy to the vehicle powered by the engine.
Many factors control the efficiency with which chemical energy is converted into useful kinetic energy or electricity, while minimizing the non-productive heat that is always produced alongside. Key variables for maximizing the efficiency of an internal combustion engine include maximizing the pressure built up during the combustion process and minimizing the temperatures of the induction air and the combustion chamber. A cooler-burning engine also offers the environmental advantage of a reduction in the amount of nitrogen oxides emitted as a by-product by the reaction of atmospheric nitrogen with oxygen species during the combustion process.
In addition to fuel and air, chemically inert materials may be introduced into the combustion chamber to absorb heat and generate pressure, thus meeting both of the above requirements for optimizing engine efficiency. In particular, water may be used to fulfil this function.
It is known that the automotive industry, for example, has previously used a selective water-injection cooling system for engine cylinders. However, the complexity of such a system and the high cost of its implementation have conspired to outweigh the benefits obtained by the process for large-scale commercialization. More specifically, water injection systems to engine cylinders have previously demanded energy input, precise control and high operating pressures, with any one of these requirements itself placing a significant constraint on potential implementation.
Other gas induction or supply systems in which humidification is of value include fuel cells, in particular proton exchange membrane (PEM) fuel cells in which gases are constantly passed over a membrane that must be kept damp for optimum performance. Humidification of circulated air in greenhouses may also be contemplated by use of the following invention.
According to a first aspect of the present invention there is provided a humidifying gas induction or supply system comprising a hydrophilic membrane surface.
Preferably, the humidifying gas induction or supply system further comprises a water reservoir integrally formed with the hydrophilic membrane surface.
A hood may be arranged to regulate an area of hydrophilic membrane surface exposed to one of the water reservoir and the gas induction or supply system.
In another aspect of the present invention there is provided an engine comprising a humidifying air induction or supply system having a hydrophilic membrane surface.
Preferably, the engine further comprises a water reservoir integrally coupled with the hydrophilic membrane surface.
In a further aspect of the present invention there is provided a motorized vehicle containing a humidifying air induction or supply system having a hydrophilic membrane surface.
Preferably, the motorized vehicle further comprises a water reservoir coupled to the hydrophilic membrane surface.
A hood may be arranged to regulate an area of hydrophilic membrane surface exposed to one of the water reservoir and the air induction system.
An exhaust system from the engine expels exhaust gases from the internal combustion process, and these exhaust gases may be used by a heat-exchanging coil in the water reservoir to heat the water contained in the water reservoir.
In another embodiment, the motorized vehicle further comprises: a fuel tank having a hydrophilic membrane surface across which water vapor pervaporates; and a channel juxtaposed the hydrophilic membrane and coupled to the water reservoir, the channel providing either a condensation trap for water vapor pervaporated from the fuel tank, and wherein the channel is coupled to the water reservoir, or a means of directing the water vapor released by the hydrophilic membrane directly into the incoming air stream. However, use of the membrane to bleed water from a fuel tank may also be actioned independently within a separate system.
Advantageously, the present invention allows the selective augmentation of water vapor into an air induction system, such as within an engine of a car, that is achieved easily (in terms of mechanical and control simplicity) and at relatively (if not insignificantly) low cost. Indeed, the inclusion of the system of the present invention is extremely desirable because it limits pollution emissions from car engines (and the like) while also improving efficiency and performance of such engines.
In a yet further aspect of the present invention, there is provided a fuel cell comprising a humidifying gas induction or supply system having a hydrophilic membrane surface.
Advantageously the current invention allows the addition of water vapor to one or more of the gas streams of a fuel cell particularly in proton exchange membrane fuel cells, preventing the proton exchange membrane from drying out and therefore optimizing the fuel cell performance.
Normal tap water or other sources of water (rather than expensive distilled water) can be used within the systems of the invention, since the hydrophilic membrane removes corrosive and damaging impurities. Furthermore, the constant delivery of water vapor into the induction air flow of an engine system avoids all problems associated with the immiscibility of water and automotive fuels, and also corrosion problems associated with the presence of liquid water; and the constant delivery of water vapor into one or more of the gases of a fuel cell optimizes performance by preventing the proton exchange membrane from drying out.